‰  NOW 25 WPM  ‰  TEXT IS FROM JULY 2014 QST  PAGE 34‰

THAT ARE CONNECTED TO THE 6R3 V AC THAT POWERS THE S METER LAMP AND THE
RECEIVERS CHASSIS GROUND RESPECTIVELY.  A VOLTAGE DOUBLER COMPRISED OF C1,
C2, D1, AND D2 CONVERTS THIS TO APPROXIMATELY 16 V DC, WHICH IS FED TO THE
NEGATIVE VOLTAGE REGULATOR U2 TO PROVIDE A STABLE 12 V DC FOR THE
OPERATIONAL AMPLIFIERS AND VOLTAGE DIVIDERS.  AMPLIFIER U1A OF A TLV2372
DUAL OPERATIONAL AMPLIFIER PROVIDES A VERY HIGH IMPEDANCE MEASUREMENT OF
THE AGC VOLTAGE CONNECTED TO INPUT AGC IN.  THE AGC VOLTAGE IS AVAILABLE ON
THE WIPER ARM OF S12 OF THE AGC ROTARY SWITCH LOCATED NEXT TO THE S METER
SEE FIGURE 1.  AMPLIFIER U1B GENERATES A STABLE REFERENCE VOLTAGE FOR THE
METER APPROXIMATELY 0R8V WHICH IS THE AGC VOLTAGE WITH NO RF INPUT SIGNAL.
THE TWO AMPLIFIER OUTPUTS DRIVE THE S METER THROUGH RESISTOR R6 AND
POTENTIOMETER R7 SENS IN SERIES WITH THE METER TO SET THE DESIRED
SENSITIVITY IN DB/S UNIT.  THE SENSITIVITY CAN BE ADJUSTED FROM ABOUT 2
‰  END OF 25 WPM TEXT  ‰  QST DE W1AW  ƒ